If a person prays the prayer, fulfilling its pillars, its preconditions and its obligatory aspects, then it is saheehah (correct). So its reward is for him, and the sin of drinking alcohol is upon him, and he is from those who mix a righteous action with another one of evil.
So whosoever does good equal to the weight of an atom shall see it. And whosoever does evil equal to the weight of an atom shall see it.
Soorah al Zalzalah (99) aayah 7 to 8
And with Allaah is the tawfeeq. And may peace and blessings be upon our Prophet Muhammad and his family and his Companions.